The objective of the proposed research is to gather information on the nature of intra-retinal interactions in the mammalian retina. The intrinsic noise manifested in the spontaneous discharge of retina ganglion cells will be used as an unknown intra-retinal input while the spontaneous discharge patterns of two or more simultaneously recorded retinal ganglion cells will provide the experimental outputs. Crosscorrelation analysis of the simultaneously observed outputs will indicate the nature of intra-retinal interactions without making technically difficult intra-retinal measurements. The electrophysiological experiments will be performed on rats surgically prepared for making simultaneous microelectrode measurements from the exposed retina.